• Korean Journal of Remote Sensing
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• v.33 no.5_1
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• pp.599-605
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• 2017

Accurate cloud discrimination in satellite images strongly affects accuracy of remotely sensed parameter produced using it. Especially, cloud contaminated pixel over ocean is one of the major error factors such as Sea Surface Temperature (SST), ocean color, and chlorophyll-a retrievals,so accurate cloud detection is essential process and it can lead to understand ocean circulation. However, static threshold method using real-time algorithm such as Moderate Resolution Imaging Spectroradiometer (MODIS), Advanced Himawari Imager (AHI) can't fully explained reflectance variability over ocean as a function of relative positions between the sun - sea surface - satellite. In this paper, we assembled a reflectance spectral library as a function of Solar Zenith Angle (SZA) and Viewing Zenith Angle (VZA) from ocean surface reflectance with clear sky condition of Advanced Himawari Imager (AHI) identified by NOAA's cloud products and spectral library is used for applying the Dynamic Time Warping (DTW) to detect cloud pixels. We compared qualitatively between AHI cloud property and our results and it showed that AHI cloud property had general tendency toward overestimation and wrongly detected clear as unknown at high SZA. We validated by visual inspection with coincident imagery and it is generally appropriate.

• Investigative Magnetic Resonance Imaging
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• v.1 no.1
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• pp.130-134
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• 1997

Purpose: To analyze contrast-enhancement pattern of stomach cancer on dynamic MRI and to verify the efficacy of intravenous contrast agent in the evaluation of stomach cancer. Materials and Methods: Twelve patients with proven stomach cancer underwent dynamic MRI. By using l.OT scanner, we obtained precontrast FLASH images, and 30, 60, 90 second delay FLASH images after intravenous contrast injection. All patients ingested one liter of water and had intramuscular injection of Buscopan just before MR study. For quantitative analysis we measured signal to noise ratio (SiN) of stomach cancer on each image, and signal difference to noise ratio (SD/N) between cancer and intraluminal fluid, cancer and the pancreas. For qualitative analysis two radiologists evaluated lesion conspicuity on each image by grading system(grade 0, 1, 2, 3: poor, fair, good, excellent). Results: SiN of stomach cancer increased gradually by time(precontrast, 30, 60, 90 second delay: 38.7, 42.5, 57.4, 65.7). SD/N between cancer and intraluminal fluid significantly increased after contrast enhancement(l.24, 25.01, 39.30, 45.89). SD/Ns between cancer and the pancreas were 10.5, 9.33, 9.99, 10.66, respectively. In qualitative analysis, precontrast images were better than postcontrast images for delineation of stomach cancer. Postcontrast images showed clear endo-Iuminal side of stomach cancer, but outer margin of stomach cancer was more distinct on precontrast images. Conclusion: Precontrast MR images are better than postcontrast MR images in the depiction of stomach cancer. Intravenous contrast agent is not imperative in the evaluation of stomach cancer.

• The Journal of Korean Physical Therapy
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• v.26 no.1
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• pp.21-26
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• 2014

Purpose: This study examined the effect of trunk stabilization exercise upon the lumbar stabilization and foot pressure on an unstable surface with back pain. Methods: The subjects of the study were 10 patients who showed the symptom of back pain with excessive lumbar curve. This study was 4 weeks, 30 minutes per session, three times a week for a total of 12 times as a result of exercise radiation imaging device and foot pressure analyzer. Results: The sacrohorizontal angle was statistically significant(p<0.05). Comparison of the difference between static right and left foot pressure ratio analysis was statistically significant(p<0.05). Dynamic right and left foot pressure comparisons for the difference was statistically significant in the analysis (p<0.05). Conclusion: Trunk stabilization exercise and the reduction of the excessive sacrohorizontal angle, and static and dynamic foot pressure imbalance reduced left and right.

• Proceedings of the IEEK Conference
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• 2005.11a
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• pp.399-402
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• 2005

For efficient and accurate diagnosis of ultrasound images, the time gain compensation (TGC) and dynamic range (DR) control of the ultrasound echo signal are important. TGC is for compensating the attenuation of the ultrasound echo signal along the depth, and DR is used to control the image contrast. In this paper, we propose an algorithm for finding the optimized values of TGC and DR automatically. For TGC, the degree of compensation is determined along the depth based on the effective attenuation estimation of ultrasound signal. For DR optimization, we introduce a novel cost function on the basis of the characteristics of ultrasound image, which provides the minimum value at the optimal DR. Experiments have been performed by applying the proposed algorithm to a real US imaging system. The results show that the algorithm automatically can determine the values of TGC and DR in realtime so that the subjective quality of the corresponding US image may be good enough for diagnosis.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.376-378
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• 2002

This work was carried out to evaluate the basic performances for 4D CT, which employed continuously rotating conebeam. The performances were evaluated with the same method as the conventional CT, because the standard method of evaluating 4D CT has not yet been established, and we think this result was helpful to establish it. 4D CT can give dynamic volume imaging data continuously and with high-speed. The results were isotropic except for the evaluation of distortion in which small distortions gradually appeared as coming off the center of phantom in longitudinal direction.

• The Korean Journal of Nuclear Medicine
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• v.26 no.2
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• pp.338-345
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• 1992

We evaluated the scintigraphic findings of sonographically atypical hemangioma, that is, a hypoechoic or heterogeneously hypoechoic nodule which contains hypoechoic areas more than 40% of the volume, and compared it with those of sonographically typical hemangioma in 26 patients with 31 nodules. Sonographically atypical hemangioma were 13 in 11 patients and sonographically typical hemangioma were 18 the 15 patients. Dynamic blood flow, planar and SPECT blood pool imaging was performed. In atypical hemangioma, increased blood pool activity was seen in 11 of 13 nodules on SPECT and in 10 of 13 nodules on planar image and increased blood flow was seen in 4 of 13 nodules on dynamic blood flow study. No significant difference in detecting increased blood pool activity between sonographically atypical and typical hemangioma. In conclusion, $^{99m}Tc-red$ blood cell SPECT is as useful in diagnosis of sonographically atypical hemangioma as in typical hemangioma and can be used as a confirmatory or complementary study.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.17 no.1
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• pp.101-107
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• 2018

In this study, the analysis of radiation noise and chattering noise of vehicle seat recliner was conducted through testing and analysis. First, operating noise was measured by seat back frame and recliner, and chattering noise was confirmed. Next, the transient dynamic analysis was performed, and the result was mapped to the acoustic analysis. Finally, the test and analysis were compared and analyzed. The results are as follow. First, it was found that the peaks appeared in common in the range of 620~650Hz, 1,240~1,290 Hz, and 1,840~1,940 Hz. It was judged that the dynamic characteristics of the recliner system overlapped with the rotation component of the motor to cause amplification of noise and vibration. Next, as a result of imaging the radiation noise analysis, it was judged that the noise radiated in the forward and backward direction has a greater influence than the direction of the rotation axis when the ear position of the person is taken as a reference.

• Journal of the Korean Institute of Telematics and Electronics B
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• v.31B no.8
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• pp.160-171
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• 1994

The wide dynamic range and severely attenuated contrast in mediastinal area appearing in typical chest radiographs have often caused difficulties in effective visualization and diagnosis of lung diseases. This paper proposes a new adaptive image enhancement technique which potentially solves this problem and there by improves observer performance through image processing. In the proposed method image processing is applied to the chest radiograph with different processing parameters for the lung field and mediastinum adaptively since there are much differences in anatomical and imaging properties between these two regions. To achieve this the chest radiograph is divided into the lung and mediastinum by gray level thresholding using the cumulative histogram and the dynamic range compression and local contrast enhancement are carried out selectively in the mediastinal region. Thereafter a gray scale transformation is performed considering the JND(just noticeable difference) characteristic for effective image displa. The processed images showed apparenty improved contrast in mediastinum and maintained moderate brightness in the lung field. No artifact could be observed. In the visibility evaluation experiment with 5 radiologists the processed images with better visibility was observed for the 5 important anatomical structures in the thorax.

• Transactions of the Korean Society of Automotive Engineers
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• v.24 no.5
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• pp.520-526
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• 2016

Squeal noise is a typical brake noise that is annoying to both passengers and pedestrians. Its frequency range is fairly wide from 1 kHz to 18 kHz, which can be distressful to people. The brake squeal noise occurs due to various mechanisms, such as the mode coupling of the brake system, self-excited vibration, unstable wear, and others. In this study, several parameters involved in the generation of a squeal noise are investigated experimentally by using a brake noise dynamometer. The speed, caliper pressure, torque, and friction coefficient are measured as functions of time on the dynamometer. The contact pressure and temperature distributions of the disc and the pad are also measured by using a thermal imaging camera and a pressure mapping system. As a result of the simultaneous measurement of the friction coefficient and squeal amplitude as functions of the velocity, it is found that the onset of the squeal may be predicted from the ${\mu}-v$ curve. It is also found that a non-uniform contact pressure causes instability and, in turn, a squeal. Based on the analysis results, design modifications of the pad are suggested for improved noise characteristics.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.15 no.2
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• pp.500-521
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• 2021

Echocardiography, an ultrasound scan of the heart, is regarded as the primary physiological test for heart disease diagnoses. How an echocardiogram is interpreted also relies intensively on the determination of the view. Some of such views are identified as standard views because of the presentation and ease of the evaluations of the major cardiac structures of them. However, finding valid cardiac views has traditionally been time-consuming, and a laborious process because medical imaging is interpreted manually by the specialist. Therefore, this study aims to speed up the diagnosis process and reduce diagnostic error by providing an automated identification of standard cardiac views based on deep learning technology. More importantly, based on a brand-new echocardiogram dataset of the Asian race, our research considers and assesses some new neural network architectures driven by action recognition in video. Finally, the research concludes and verifies that these methods aggregating dynamic information will receive a stronger classification effect.